This invention relates to a cell treatment apparatus and method. More specifically, this invention relates to a treatment apparatus and method using at least one laser beam to porate (create a pore or poration) in a patient's cells in vivo.
Various techniques have been used, at least experimentally, for transfection of cells (i.e., insertion of new genetic material into the DNA structure of cells).
One technique for transfection of cells has used laser poration. This approach has been performed in vitro using a laser beam to porate a single cell at a time under a specially adapted microscope. The microscope allows the direct puncture of the cell membrane in the presence of the gene. Specifically, an operator directs the laser beam towards an individual cell and the puncture of the cell membrane allows genetic material on the same slide as the cell to enter into the cell. This approach is labor intensive and not practical to use in vivo. This laser poration technique is described in the article by Tao et al. entitled "Direct Gene Transfer Into Human Cultured Cells Facilitated By Laser Micropuncture of Cell Membrane" in the Proceedings of the National Academy of Science in 1987; 84:4180-4184.
Other approaches to transfection of cells have included chemical methods or electrical poration used in a cell culture, but such methods are not readily applicable in vivo. In other words, such methods may allow treatment of cells which have been removed from the patient, but do not allow treatment of cells remaining with the patient (human or animal).
The Nabel et al. article entitled "Site-Specific Gene Expression in Vivo by Direct Gene Transfer Into the Arterial Wall" in Science in 1990; 249(4974):1285-1288 discloses a technique for transfecting genes in vivo which has been used in the arteries of pigs. This technique uses a catheter with a dual balloon system at the tip of the catheter. The two balloons are inflated to create a temporary chamber which allows the exposure of the arterial wall to a viral transporting agent in solution. This has been used successfully to transfect the arterial wall with a DNA-plasmid having a viral carrier. However, this double balloon method requires 30 minutes to bathe the arterial wall with the DNA-plasmid to be effective. This is not feasible in certain applications such as in the coronary circulation. Moreover, the time required for such a technique to work may pose severe problems even at other locations within the arteries of an animal or human.
The Lim et al. article entitled "Direct In Vivo Gene Transfer Into the Coronary and Peripheral Vasculatures of the Intact Dog" appearing in Circulation, volume 83, no. 6, June 1991, pages 2007-2011, discloses a technique where endothelial cells are removed from the test animal and then transfected prior to reintroduction into the animal. In addition to that in vitro technique, the article describes in vivo transfection of arteries of dogs using catheters placed in peripheral vessels of the dogs. Proximal and distal lumens of the vessels were occluded with removable ligatures. In somewhat similar fashion to the dual balloon system, a temporary chamber is established and a transfection solution is supplied into that temporary chamber within the vessels of the animal. The article describes allowing the transfection solution to remain in the vessel for one hour.
Apart from the problems in developing medically effective techniques for using cell transfection, medical techniques for applying drugs to a patient have encountered problems. Specifically, a drug must be given in sufficient dosage that it will have the desired effect when a portion of it reaches the area of the body which the drug is supposed to treat. However, the dosage must not be so high that the portion of the drug which reaches other parts of the body causes unacceptable side effects. In other words, it has been difficult to introduce a drug into a patient without having significant portions of the drug reach portions of the body other than the portion where one wanted the drug to act. If one lowers the dosage of the drug, it may fail to reach the desired location within the body in sufficient quantity to have the desired effect. However, if one raises the dosage, the unintended consequences of the drug may increase in magnitude.
Various techniques have been developed to cause drugs to concentrate within a certain desired site of the body of a patient. Although such techniques have been quite useful, they still fail to give the desired control over the application of drugs that is necessary or desirable for certain conditions and circumstances.